Band Selection Switch Circuit for Multi-Band Tx/Rx Isolation
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Solution Overview
Problem
Conventional band selection switches in power amplifier systems face deteriorated isolation characteristics when both transmission and reception signal paths are simultaneously active, particularly in systems using triplexers and quadplexers.
Innovation Solution
The band selection switch apparatus employs a configuration with multiple series and shunt switches, each with specific switch elements connected in series and shunt configurations to maintain isolation and withstand voltages corresponding to transmission and reception powers, ensuring synchronized and complementary switching operations across multiple bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional band selection switch uses a simple series switch configuration, then the device complexity is low, but the isolation characteristics between transmission and reception signal paths deteriorate when both paths are simultaneously active
Solution Approach 1:
The switch is divided into multiple independent switch units (first switch unit, second switch unit, third switch unit), each handling specific signal paths. This segmentation allows independent control of transmission and reception paths, improving isolation characteristics while maintaining manageable complexity through modular design.
Solution Approach 2:
A shunt switch is introduced as an intermediary element connected between the series switch and ground. This shunt switch acts as a mediator to provide additional isolation by diverting unwanted signals to ground, thereby improving isolation characteristics between simultaneous transmission and reception paths without significantly increasing overall device complexity.
2Adaptability or versatility
If a band selection switch is designed to support multiple frequency bands with simultaneous transmission and reception, then the adaptability is improved, but the device complexity increases due to additional switch configurations
Solution Approach 1:
The band selection switch is designed with multiple switch units that can be configured to support various frequency bands (first band, second band, third band) and multiple operating modes (transmission, reception, simultaneous transmission and reception). This universal design allows a single device to handle multiple functions and bands, improving adaptability while controlling complexity through standardized switch unit structures.
Solution Approach 2:
The switch configuration is made dynamic through independent control of multiple switch units and their associated shunt switches. Each switch unit can be independently activated or deactivated based on the required operating mode, allowing the device to adapt its configuration dynamically to support different frequency bands and simultaneous transmission-reception operations without requiring a completely different structure for each mode.
3Reliability
If the switch elements have high withstand voltage to handle transmission power, then the reliability is improved, but the insertion loss increases due to additional series switch elements
Solution Approach 1:
The series switch path is segmented into multiple switch elements arranged in series, where each element handles a portion of the total voltage stress. This segmentation allows each individual switch element to have lower withstand voltage requirements while collectively handling the full transmission power voltage, thereby reducing insertion loss per element while maintaining overall reliability.
Solution Approach 2:
Multiple switch elements are combined in series to create a composite switching structure that collectively provides the required high withstand voltage capability. This composite approach distributes the voltage stress across multiple elements, allowing each element to operate at lower voltage levels with lower insertion loss, while the series combination achieves the necessary overall voltage handling capability.
Data Source
AI summary
A band selection switch apparatus includes: a first switch including a first series switch disposed between a transmission input terminal and a first transmission and reception terminal; a second switch including a second series switch disposed between the transmission input terminal and a first transmission terminal; and a third switch including a third series switch disposed between a first reception output terminal and the first transmission and reception terminal. The first series switch includes a first series switch circuit including first series switch elements connected between the transmission input terminal and a first intermediate node, a second series switch circuit including second series switch elements connected between the first intermediate node and the first transmission and reception terminal, and a first shunt switch circuit including first shunt switch elements connected between the first intermediate node and a ground.